Get a pre- and post feeding weight taken to see how much she takes in in an average nursing session. To do this, start her with a clean diaper, nurse, weigh with the same diaper, whether dirty or wet.

Have your DD evaluated for a tongue or lip tie. Have the IBCLC examine you for signs of insufficient glandular tissue or hypoplastic breasts. Could you have retained placenta? Have you ever had signs of PCOS?